MCQs on Waves Optics
Q: Polarisation phenomenon explains which nature of light?
a) Transverse
b) longitudinal
c) Both transverse and longitudinal
d) geometrical
Answer: (a) Transverse
Q: A narrow slit is taken and a parallel beam of moving electrons is incident normally on it. At a larger distance from the slit, a fluorescent screen is placed. Which of the following statement is true if the size of the slit is further narrowed?
a) The diffraction pattern cannot be observed on the screen
b) The angular width of the central maxima of the diffraction pattern will increase
c) The angular width of the central maxima of the diffraction pattern will decrease
d) The angular width of the central maxima of the diffraction pattern remains the same
Answer: (c) The angular width of the central maxima of the diffraction pattern will decrease
Q: How does the diffraction band of blue light look in comparison with the red light?
a) No changes
b) Diffraction pattern becomes narrower
c) Diffraction pattern becomes broader
d) Diffraction pattern disappears
Answer: (b) Diffraction pattern becomes narrower
Q: Two coherent sources of light can be obtained from
a) Two different lamps
b) Two different lamps but of the same colour
c) Two different lamps of the same colour and having the same colour
d) None of these
Answer: (d) None of these
Q: Which of the following phenomenon is not explained by Huygen’s wave theory?
a) Diffraction
b) Interference
c) Polarisation
d) Photoelectric effect
Answer: (d) Photoelectric effect
Q: What is the value of coherent time if L is the coherent length and c is the velocity of light?
a) cL
b) L/c
c) c/L
d) 1/Lc
Answer: (b) L/c
Q: The ratio of the amplitude of the two sources producing interference 3 : 5, the ratio of intensities at maxima and minima is
a) 25:6
b) 5:3
c) 16:1
d) 25:9
Answer: (c) 16:1
Q: The colours on the soap bubble is due to
a) Interference
b) Polarisation
c) Diffraction
d) Reflection
Answer: (a) Interference
Q: Which of the following statements indicates that light waves are transverse?
a )Light waves can be polarised
b) Light waves can show interference
c) Light waves undergo diffraction
d) They travel in the vacuum
Answer: (a) Light waves can be polarised
Q: In Young’s double-slit experiment, the phase difference between the light waves reaching the third bright fringe from the central fringe will be (λ=6000 Å)
a) Zero
b) 2π
c) 4π
d) 6π
Answer: 6π
